json2: decode time.Time, supporting unix timestamps (like json), as well as rfc3339 datetimes (#16653)

vlib/x/json2/decode_struct_test.v

@@ -8,7 +8,7 @@ const fixed_time = time.Time{
 	hour: 13
 	minute: 54
 	second: 25
-	unix: 0
+	unix: 1647006865
 }
 
 type StringAlias = string
@@ -77,4 +77,15 @@ fn test_types() {
 	assert json.decode[StructType[int]]('{"val": "false"}')!.val == 0
 	assert json.decode[StructType[int]]('{"val": true}')!.val == 1
 	assert json.decode[StructType[int]]('{"val": false}')!.val == 0
+
+	assert json.decode[StructType[time.Time]]('{"val": "2022-03-11T13:54:25.000Z"}')!.val == fixed_time
+	assert json.decode[StructType[time.Time]]('{"val": "2022-03-11 13:54:25.000"}')!.val == fixed_time
+	assert json.decode[StructType[time.Time]]('{"val": 1647006865}')!.val == fixed_time
+	assert json.decode[StructType[time.Time]]('{"val": "1647006865"}')!.val == fixed_time
+	if x := json.decode[StructType[time.Time]]('{"val": "invalid time"}') {
+		assert false
+	} else {
+		// dump(err)
+		assert true
+	}
 }

vlib/x/json2/encode_struct_test.v

@@ -8,7 +8,7 @@ const fixed_time = time.Time{
 	hour: 13
 	minute: 54
 	second: 25
-	unix: 1647017665
+	unix: 1647006865
 }
 
 type StringAlias = string

vlib/x/json2/json2.v

@@ -50,7 +50,7 @@ pub fn decode[T](src string) !T {
 		} $else $if field.typ is string {
 			typ.$(field.name) = res[field.name]!.str()
 		} $else $if field.typ is time.Time {
-			// typ.$(field.name) = res[field.name]!.str()
+			typ.$(field.name) = res[field.name]!.to_time()!
 		} $else {
 			return error("The type of `${field.name}` can't be decoded. Please open an issue at https://github.com/vlang/v/issues/new/choose")
 		}
@@ -251,3 +251,38 @@ pub fn (f Any) as_map() map[string]Any {
 		'0': f
 	}
 }
+
+// to_time uses `Any` as a time.Time.
+pub fn (f Any) to_time() !time.Time {
+	match f {
+		time.Time {
+			return f
+		}
+		i64 {
+			return time.unix(f)
+		}
+		string {
+			is_rfc3339 := f.len == 24 && f[23] == `Z` && f[10] == `T`
+			if is_rfc3339 {
+				return time.parse_rfc3339(f)!
+			}
+			mut is_unix_timestamp := true
+			for c in f {
+				if c == `-` || (c >= `0` && c <= `9`) {
+					continue
+				}
+				is_unix_timestamp = false
+				break
+			}
+			if is_unix_timestamp {
+				return time.unix(f.i64())
+			}
+			// TODO - parse_iso8601
+			// TODO - parse_rfc2822
+			return time.parse(f)!
+		}
+		else {
+			return error('not a time value: ${f} of type: ${f.type_name()}')
+		}
+	}
+}